Table 1

Sample sizes and smoking status across data collection waves

Wave	Time period	Survey mode	Non-smokers	Smokers	Total
1	July 2001	Telephone	463	442	905
2	December 2001	Telephone	484	422	906
3	December 2002	Telephone	459	452	911
4	December 2003	Telephone	956	843	1799
5	June 2004	Telephone	962	835	1797
6	December 2005	Web	1609	366	1975
7	June 2006	Web	1994	466	2440
8	December 2006	Web	1512	454	1966
9	June 2007	Web	1403	357	1760
10	December 2007	Web	982	257	1239
11	June 2008	Web	797	231	1028

Note that the web-respondents in waves 6 through 11 are not unique.